Les travaux menés durant cette thèse ont visé à évaluer la pertinence de la plante aquatique Myriophyllum aquaticum pour l'étude de la biodisponibilité du cuivre dans des sédiments ainsi que l'intérêt de la technique du gradient de diffusion en couche mince (DGT) comme outil biomimétique de cette plante. Une première expérimentation réalisée avec la plante M.aquaticum exposée selon le protocole du biotest normalisé (sous forme de verticilles) dans des sédiments artificiels dopés en cuivre a montré que ce biotest semble être un outil intéressant pour l'évaluation de la toxicité de sédiments contaminés en cuivre. En outre, aucune corrélation n'a été observée entre les mesures DGT et la bioaccumulation dans la plante M.aquaticum. Ceci est probablement lié aux conditions d'exposition des plantes. En effet, le développement des racines se faisant au cours de l'expérimentation, les processus d'incorporation du métal dans la plante ne sont donc pas constants au cours de l'expérience. Suite à ces résultats nous avons réalisé deux autres séries d'expérimentations (hydroponie et Rhizotest) dans lesquelles, les plantes ont été exposées selon un protocole modifié (plantes ayant déjà développé des racines avant leur exposition dans le sédiment). Ces expérimentations nous ont permis de montrer que la plante M.aquaticum est plutôt sensible au cuivre et qu'elle a une forte capacité à l'accumuler. De plus, les résultats obtenus ont permis de montrer que la technique DGT semble être un bon outil biomimétique de cette plante dans le cas où elle est exposée avec des racines car le prélèvement par la plante est limité par la capacité de la phase solide à réapprovisionner le métal en solution. / The work carried out during this thesis aimed to assess the relevance of the aquatic plant Myriophyllum aquaticum to study the bioavailability of copper in sediments as well as the interest of the technique of diffusion gradient in thin film (DGT) as a biomimetic tool of this plant. A first experiment, performed with the plant M.aquaticum exposed according to the protocol of the standardized bioassay (as whorls) in an artificial sediment spiked with copper, showed that this bioassay appears to be a useful tool for assessing the toxicity of contaminated sediments copper. Furthermore, no correlation was observed between DGT measurements and bioaccumulation in the M.aquaticum plant. This is probably due to the exposure conditions of the plants. In fact, as the root development occurs during the experiment, the process of incorporating the metal into the plant is therefore not constant throughout the experiment.Following these results we conducted two other series of experiments (hydropony and Rhizotest) in which, plants were exposed following a modified protocol (plants having already developed roots before their exposure in the sediment). These experiments showed that the plant M.aquaticum is rather sensitive to copper and has a strong ability to accumulate it. Futhermore, the results have shown that the DGT technique seems to be a good biomimetic tool for this plant when it is exposed by roots because the plant uptake is limited by the capacity of the solid phase to replenish the metal in solution.

<p>&nbsp; &nbsp; Razvojem testova inhibicije rasta na vrstama&nbsp; roda&nbsp;<em> Myriophyllum&nbsp;</em> ispitan je<br />potencijal&nbsp; vrsta <em>Myriophyllum&nbsp; aquaticum</em>&nbsp; (Vell.) Verd.&nbsp; i&nbsp;<em> Myriophyllum spicatum</em>&nbsp; L. u<br />ekolo&scaron;koj proceni rizika&nbsp; od herbicida i kontrole kvaliteta sedimenta. Ispitana je<br />primenljivost&nbsp; kontaktnog testa toksičnosti sedimenta sa vrstom&nbsp; M. aquaticum&nbsp; u<br />retrospektivnoj&nbsp; proceni&nbsp; rizika&nbsp; sedimenta&nbsp; na uzorcima iz prirode&nbsp; &ndash;&nbsp; na sedimentu&nbsp; reka Tami&scaron;, Krivaja i Jegrička.&nbsp; Testom toksičnosti sedimenta obogaćenog atrazinom,<br />analiziran je i potencijal kontaktnog testa u preventivnoj proceni rizika od hemikalija<br />koje pokazuju afinitet vezivanja za sediment. Testovima inhibicije rasta <em>M. aquaticum</em><br />i&nbsp; <em>M. spicatum&nbsp;</em> u voda-sediment sistemu ispitana je osetljivost i mogućnost primene<br />metode u preventivnoj proceni rizika od herbicida i regulatora rasta.<br />&nbsp; &nbsp; Deo rezultata dobijenih u radu uključen je u zavr&scaron;ne izve&scaron;taje internacionalnih<br />testova interkalibracije metoda,&nbsp; a kao rezultat ovih aktivnosti usvojene su nove<br />standardne metode na ukorenjenim akvatičnim makrofitama ISO 16191/2013 i OECD 239/2014.<br />&nbsp; &nbsp; &nbsp; Na osnovu istraživanja, zaključeno je da je kontaktni test toksičnosti<br />sedimenta&nbsp; jednostavan i lak za izvođenje, kao i da je vrsta<em>&nbsp; M. aquaticum</em>&nbsp; u jedno-komponentnom sistemu (sediment)&nbsp; adekvatan test model. Rastom kontrolnih biljaka, niskom varijabilno&scaron;ću i visokom osetljivo&scaron;ću biolo&scaron;kih&nbsp; odgovora zadovoljen je kriterijum validnosti testa. Preporučeno je kori&scaron;ćenje dodatne kontrole&nbsp; u&nbsp; slučajevima kada postoje značajna odstupanja u strukturi između&nbsp; standardnog sintetičkog kontrolnog i&nbsp; testiranog prirodnog sedimenta.&nbsp; Kontaktnim&nbsp; testom toksičnosti sedimenta obogaćenog&nbsp; atrazinom&nbsp; pokazano je da se ovaj test&nbsp; može smatrati potencijalno dobrom metodom za pro&scaron;irenje ekolo&scaron;ke procene rizika od hemikalija koje pokazuju afinitet vezivanja za sediment.<br />&nbsp; &nbsp; Ispitivanjem potencijala&nbsp; testa&nbsp; inhibicije rasta vrsta roda&nbsp;<em> Myriophyllum</em>&nbsp; u voda-sediment sistemu&nbsp; utvrđeno je da su testovi&nbsp; izvodljivi u praksi, da pokazuju&nbsp; visoki stepen stabilnosti, statističku snagu i malu varijabilnost&nbsp; većine&nbsp; ispitivanih parametara rasta. Poređenjem testova sa vrstama&nbsp;<em> M. aquaticum</em>&nbsp; i&nbsp;<em> M. spicatum</em>, nije utvrđena značajna&nbsp; razlika u osetljivosti na odabrane herbicide.&nbsp; Osetljivost&nbsp; testova na vrstama roda&nbsp; <em>Myriophyllum</em>&nbsp; i standardnih&nbsp; Lemna&nbsp; testova je bila slična,&nbsp; osim u slučaju auksin simulatora gde su&nbsp; vrste roda <em>Myriophyllum</em>&nbsp; sp. bile osetljivije,&nbsp; &scaron;to&nbsp; ukazuje&nbsp; na njihovu primenljivost u proceni rizika od pesticida specifičnog mehanizma toksičnog dejstva.<br />&nbsp; &nbsp; Iako&nbsp; obe vrste roda&nbsp; <em>Myriophyllum</em>&nbsp; imaju&nbsp; prednosti i nedostatke&nbsp; kao test<br />organizmi,&nbsp; vrste se&nbsp; mogu&nbsp; smatrati reprezentativnim akvatičnim ukorenjenim<br />makrofitama i predstavljati&nbsp; adekvatne&nbsp; dopunske test vrste u vi&scaron;im nivoima ekolo&scaron;ke<br />procene rizika od herbicida i regulatora rasta.&nbsp; Takođe, vrsta <em>M. aquaticum&nbsp; </em>je pogodna za&nbsp; testiranje u&nbsp; različitim test sistemima,&nbsp; a samim tim&nbsp; ima i veći&nbsp; potencijal primene u preventivnoj, ali i retrospektivnoj ekolo&scaron;koj proceni rizika.</p> / <p>Growth inhibition tests on <em>Myriophyllum&nbsp; aquaticum</em>&nbsp; (Vell.) Verd.&nbsp; and <em>Myriophyllum spicatum</em>&nbsp; L.&nbsp; were conducted in order to assess their use in refined risk assessment&nbsp; of chemicals, as well as in&nbsp; sediment&nbsp; risk assessment.&nbsp; The applicability, stability and sensitivity of the&nbsp;<em> M.&nbsp; aquaticum&nbsp; </em>sediment contact test on natural sediments (from rivers Tami&scaron;, Krivaja and&nbsp; Jegrička) was assessed for use in retrospective ecological risk assessment (ERA). The potential use of the spiked sediment contact test in risk assessment&nbsp; of&nbsp; sediment bound chemicals was&nbsp; also investigated. The sensitivity and applicability of the growth inhibition tests on&nbsp;<em> M. aquaticum</em>&nbsp; and&nbsp; <em>Myriophyllum </em>spicatum&nbsp; in a water-sediment system was assessed for potential use in prospective ERA of plant protection products.</p><p>A part of the results of this study was included in the final report of the two&nbsp; international ring tests, which resulted with new standardised methods with rooted macrophytes:&nbsp; ISO 16191/2013 i&nbsp; OECD&nbsp; 239/2014. Tests on&nbsp; <em>Myriophyllum</em>&nbsp; species were compared to standard Lemna&nbsp; tests.&nbsp; Test substances in <em>M. aquaticum</em>&nbsp; and&nbsp; <em>Lemna minor&nbsp; L</em>. tests were 3,5 dichlorphenol, atrazine, isoproturon, trifluralin, 2,4 D and dicamba, while substances used in&nbsp;<em> M. spicatum&nbsp;</em> tests were atrazine, isoproturon and 2,4 D.</p><p>The sediment contact test proved to be simple and robust, while <em>M. aquaticum</em> can be considered as an adequate test model in a one-compartment (sediment) test. The validity criteria regarding control plant growth and variability was met. The use of an additional control is suggested when testing of sediments with considerably different properties of the standard synthetic control is taking place.&nbsp; The spiked sediment contact tests with atrazine showed that the method could be applied in prospective risk assessment of sediment bound chemicals.</p><p>The water-sediment growth inhibition test with&nbsp; <em>Myriophyllum</em>&nbsp; species proved to be applicable in practice, with high stability, statistical power and low variability of the majority of the growth parameters.<em>&nbsp; M. aquaticum&nbsp;</em> and&nbsp; M. spicatum&nbsp; didn&rsquo;t show major&nbsp; differences&nbsp; in sensitivity to tested substance.&nbsp; The sensitivity of&nbsp; <em>Myriophyllum</em> and&nbsp; Lemna&nbsp; tests was also similar, except to auxin simulators, where&nbsp; <em>Myriophyllum </em>species were considerably more sensitive, which makes them adequate&nbsp; candidates for use in risk assessment of chemicals with specific mode of action.</p><p>Even though both&nbsp; <em>Myriophyllum</em>&nbsp; species show advantages and disadvantages as test organisms, they can be regarded as representative rooted aquatic macrophyte species and additional test species in refined risk assessment of herbicides and growth regulators. &nbsp;Also,&nbsp; <em>M. aquaticum&nbsp; </em>can be tested in various test syytems, which makes this species &nbsp;applicable in prospective as well as retrospective ecological risk assessment.</p>

Made available in DSpace on 2016-06-02T19:31:42Z (GMT). No. of bitstreams: 1 2466.pdf: 1815118 bytes, checksum: 2691e87ca8ac1a5d9be7670c3b228b19 (MD5) Previous issue date: 2009-06-02 / Universidade Federal de Minas Gerais / The oxidative aerobic processes contribute with large amounts of nutrients in dissolved and particulate forms for the metabolism microbial water. In that context, this study described the oxygen consumption kinetics during the aerobic mineralization of Myriophyllum aquaticum and also evaluated the possible effects of nutrients addiction, the chemical composition and temperature on the decomposition. The aquatic macrophyte was collected in the coastal region of the Monjolinho reservoir (220 00' S and 47054' W; SP, Brazil). In the laboratory part of the plant fragments were subjected to leaching for extraction of the dissolved organic matter (DOM). In the laboratory, part of the plant fragments was subjected to leaching to extract the particulate fraction (POM). The mineralization chambers were set up (n = 96) with different N and P concentrations, entire detritus or lignocellulosic matrix (i.e. fibers) in two phenological stages (senescent or green) under two temperature (16 and 25 ºC), totaling 32 treatments. The concentrations of dissolved oxygen (DO) were determined periodically in the chambers for 80 days. The results were adjusted to a kinetic model of first-order. Different concentrations of N and P did not interfere in the microbial metabolism when the experiments with full detritus and lignocellulosic matrix were analyzed separately. Moreover, in experiments that include the mineralization of macrophytes under natural conditions (with reservoir water), was favoring the mineralization rather than immobilization. However, the independent analysis of the concentrations of N and P showed that the same condition of temperature and type of fragment (green or senescent), the kD was approximately 2 times greater in treatments with full detritus for those with only lignocellulosic matrix, which showed higher C: P and smaller quantities of lignin in their original chemical composition. The Q10 has shown similarities between the treatments, regardless of chemical composition (entire or fibers), but differences in relation to the plant phenological stage (ranging from 1.75 to 2.06). Regarding the stoichiometry O/N was an expense of greater oxygen for nitrification in treatments with full litter (mean = 1%) compared to treatment with lignocellulosic matrix (mean = 0.6%). The quality of detritus was the most important variable in the mineralization of macrophytes the temperature has served as a secondary factor. / Os processos oxidativos aeróbios contribuem com grande quantidade de nutrientes nas formas dissolvida e particulada para o metabolismo da microbiota aquática. Nesse contexto, este estudo descreveu as cinéticas de consumo de oxigênio durante a mineralização aeróbia de Myriophyllum aquaticum, avaliando os possíveis efeitos da adição de nutrientes, composição química do detrito e da temperatura na decomposição. A macrófita aquática foi coletada na região litorânea do reservatório do Monjolinho (220 00' S e 470 54' O; SP, Brasil). Em laboratório parte dos fragmentos das plantas foram submetidos à lixiviação para extração da fração dissolvida (MOD). Foram montadas câmaras de decomposição (n = 96) com diferentes concentrações de N e P, contendo detrito íntegro ou matriz lignocelulósica (i.e. fibras) em dois estágios fenológicos (verde ou senescente) e submetidas a duas condições de temperatura (16 e 25 ºC), totalizando 32 tratamentos. As concentrações de oxigênio dissolvido (OD) foram determinadas periodicamente nas câmaras durante 80 dias. Os resultados foram ajustados a um modelo cinético de primeira-ordem. As diferentes concentrações de N e P não interferiram no metabolismo microbiano quando os experimentos com detrito íntegro e matriz lignocelulósica foram analisados separadamente. Por outro lado, nos experimentos que contemplaram a mineralização da macrófita sem enriquecimento com N e P (água do reservatório), houve o favorecimento da mineralização em detrimento da imobilização. Porém, a análise independente das concentrações de N e P mostraram que numa mesma condição de temperatura e tipo de fragmento (verde ou senescente), o kD foi aproximadamente 2 vezes maior nos tratamentos com detrito íntegro em relação aqueles somente com matriz lignocelulósica, que apresentou maior relação C:P e menores quantidades de lignina em sua composição química inicial. O Q10 mostrou similaridade entre os tratamentos, independente da composição química (integral ou fibras), porém, diferença em relação ao estágio fenológico da planta (variaram de 1,75 a 2,06). Com relação à estequiometria O/N houve um gasto maior de oxigênio para a nitrificação nos tratamentos com detritos íntegros (média = 1%) em relação aos tratamentos com matriz lignocelulósica (média = 0,6%). A qualidade do detrito constituiu se na variável mais importante na mineralização da macrófita, já a temperatura atuou como um fator secundário.